Containers are made from various materials, including glass, metal and plastic. Recently, plastic containers have been favored for their light weight construction and low cost. In particular, plastic containers can be made by known molding and thermoforming processes. In order to withstand shipping, handling and storage, the plastic should be robust. Preferred plastics today include PET and high-impact polystyrene. In particular, the plastics are selected so as to resist fracturing upon the application of expected and unexpected forces.
Many of the known sealed containers include a body defining a cavity for receiving material and a lid or cover for sealing the cavity. In some containers, the cover is connected to the body by a mechanical interconnection, such as a snap-fit connection or threaded connection. In other containers, the cover can be connected to the body by adhesives and heat sealing. In some of these containers, the cover can be easily removed from the body to allow for access to the stored material. With small containers, however, removal of the cover can be difficult.
Other containers can be configured so that cover remains connected to the body, and the body can be fractured upon the application of force. To provide a fracturable opening while maintaining the general strength of a container made from PET or high-impact polystyrene, one of the walls of the container will have a weakened section, such as a thinned wall section or perforations of the wall.
Plastic containers, including a weakened section, are often made by a basic molding process, as the wall thickness can be varied during the molding process. Other plastic containers with a weakened section are thermoformed, where the weakened section is a result of cutting or perforating. Due to the reduced wall thickness associated with thermoformed containers, the weakened section is produced on generally flat sections of the containers so that a minimum wall thickness can be maintained, thereby providing a measure of structural stability, while weakening a section sufficiently to be fracturable.
The weakened section allows the package to maintain a desired structural integrity inherent in the PET or high-impact polystyrene along the majority of the container body. However, by weakening a section of the container body, the container can be undesirably compromised by the application of force on the container body or as a result of internal pressure within the container, resulting in an unsealed container.
To reduce the impact of employing a weakened section, known thermoformed containers position the weakened section to extend along a corner or otherwise smaller section of the container. The resulting small opening from this minimized weakened section does not provide for free flow of product stored in the cavity under the influence of gravity. While this aids in reducing unintended dispensation from the cavity, a user must squeeze or otherwise deform the container rather than simply tilting the container to dispense the contents.
Many containers include an inner coating or layer to provide further protection for the contents. Although these coatings are effective for particular materials to be stored in the container or for particular environments, they are not intended to accommodate for the compromised integrity of the container body resulting from the weakened wall section.